// Copyright (c) 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CC_ANIMATION_SCROLL_OFFSET_ANIMATIONS_H_
#define CC_ANIMATION_SCROLL_OFFSET_ANIMATIONS_H_

#include <unordered_map>

#include "cc/animation/scroll_offset_animations_impl.h"
#include "cc/trees/mutator_host_client.h"

namespace cc {

// A ScrollOffsetAnimationUpdate represents a change on the main thread
// that may impact an impl-only scroll offset animation.
// Note that this class only exists on the main thread.
struct CC_ANIMATION_EXPORT ScrollOffsetAnimationUpdate {
    ScrollOffsetAnimationUpdate();
    explicit ScrollOffsetAnimationUpdate(ElementId);

    // The element to which this update applies.
    ElementId element_id_;

    // The amount by which the scroll offset is changed on the main thread.
    gfx::Vector2dF adjustment_;

    // If set to true, abort the currently running impl only scroll offset
    // animation running on cc and finish it on the main thread.
    bool takeover_;
};

// ScrollOffsetAnimations contains a list of ScrollOffsetAnimationUpdates.
// PushPropertiesTo is called during commit time and the necessary update is
// made to the impl-only animation.
class CC_ANIMATION_EXPORT ScrollOffsetAnimations {
public:
    explicit ScrollOffsetAnimations(AnimationHost* animation_host);
    ~ScrollOffsetAnimations();

    void AddAdjustmentUpdate(ElementId, gfx::Vector2dF adjustment);
    void AddTakeoverUpdate(ElementId);

    bool HasUpdatesForTesting() const;

    // Goes through the updates in the order in which they're added and calls the
    // appropriate handler for each update.
    void PushPropertiesTo(ScrollOffsetAnimationsImpl*);

private:
    ScrollOffsetAnimationUpdate GetUpdateForElementId(ElementId) const;

    using ElementToUpdateMap = std::unordered_map<ElementId, ScrollOffsetAnimationUpdate, ElementIdHash>;
    ElementToUpdateMap element_to_update_map_;

    AnimationHost* animation_host_;
};

} // namespace cc

#endif // CC_ANIMATION_SCROLL_OFFSET_ANIMATIONS_H_
